Alternatively, you may consider taking A levels after your SPM, and then try to apply for entrance into NUS Pharmacy course. Recommended subjects include Biology, Physics, Chemistry, Maths. Since you mentioned that your family isn't that rich, i guess you must work really hard to score at least 9 A's for SPM, and then get 100% tuition fee waiver for A levels ( which is available in most of the colleges). As NUS Pharmacy course is highly competitive, you may need straight A's for your A levels to be considered for admission. Moreover, depending on your A level results, you may be considered for ASEAN Undergraduate Scholarship. Good luck.

Personally, I feel that taking the A levels route is better than the STPM route. Although it is true that STPM is almost as recognized as A levels, and in fact much cheaper, taking A levels examination is a much wiser choice. Firstly, STPM ain't easy. I have heard of people who aced SPM, but did below average/badly for STPM. In this case, they waste 1.5-2 years of their life, and are not able to enter local universities. Most likely they will be going for private colleges, or overseas if they are rich. Even if you ace your STPM, it is not guaranteed that you will get a place in local universities/the course of your choice. Just my 2 cents.